first because it's a broken line we know it's an inequality.
next we find the slope we can take points (0,4) and (2,0) thus (y2-y1)÷(x2-x1)
substituting any value of x for either x1 or x2 and any value of y for y1 and y2 we can get
slope is -2
so now we can take either points to find the equation by the formula
y-yo=m (x-xo) where m is slope
after substitution we can get
y-4=-2 (x-0)
y=-2x+4